Alternative Power Mobility Controls: Where to Start & What to Consider

Rehab professionals working with children face many challenges
when it comes to finding independent access for power
mobility. A realistic expectation is that it will take time for any
child to achieve independence. A power mobility evaluation can take
a significant number of appointments, and all team members must
be invested in the final outcome of independent power mobility for
success to occur.

For many children, the first attempt at driving a power wheelchair
is a foreign feeling and a brand-new experience. They may have never
moved themselves through space before. They will likely hit things
both accidentally and on purpose. The thing to look at when they do
strike an object is that they stop and don't try to continue to drive
through the object. When walking, we accidentally hit things as well,
but we stop and make corrections to our path, and this should be the
same expectation for children driving power mobility.

Getting Started

Obviously, most children don't just get into a power wheelchair and
drive. It takes time to develop the skills they need.

The first step is to allow them to explore the power wheelchair in
a safe manner. They need to experience that when they hit the switch
or deflect the joystick, they move the wheelchair. They also need to
learn the boundaries of the wheelchair and learn to avoid hitting
objects. After a period of time, they will understand that when they
hold the switch or move the joystick, the chair goes. The learning
curve may extend a little longer with alternative drive controls.

When evaluating for the most appropriate control device, a
proportional joystick should be evaluated first, since it provides the
most direct control of a power wheelchair. A proportional joystick
allows fine-tuning of speed, as well as multiple directional controls
just by defl ecting or reducing the deflection of the joystick. It is the
most direct access method, and if the child has enough control,
it will provide the easiest way to control movements of the power
wheelchair within his or her environment.

Just because a standard joystick doesn't work doesn't mean that
we move on to a different type of access. There are many joysticks
that vary in the amount of force that must be applied, as well as a
variety of joystick handles that can be used to optimize access to the joystick. Remember to try as many options and mounting locations
for access as possible before ruling a joystick out as an option.
Custom-mounted locations may provide proper access and good
control with a joystick, but may require some serious customization
of the wheelchair. Also, keep in mind that fine-tuning the programming
can make a significant difference in controlling a wheelchair.

Alternatives to the Joystick

If a joystick has been ruled out as an access method, there are other
options to consider.

If a child has gross motor control of one of his or her extremities,
but not enough fine motor control to utilize a joystick, then it may
be possible to use switches for driving. Switches offer the next best
direct access method to a joystick. A switch can be pressed and held
to move the wheelchair in a desired direction. When using multiple
switches, a child has the option to press and hold two switches at
the same time. This means that a child can control a wheelchair in
multiple directions with his or her gross motor movement pattern.

There is a variety of switch arrays available: five switches, four
switches, three switches, two switches and one switch. All of these
methods require a certain level of cognition to drive the power
wheelchair. The lower the number of switches, the greater the cognitive
requirements, since a switch no longer represents control of just
one direction. As we get to a lower number of switches, we may want
to consider other types of alternative control before utilizing a twoswitch
or one-switch type of driving system.

If switches have been ruled out, we need to look at what other
body parts may be able to be utilized for access to control the
wheelchair. A head array and sip and puff are two other common
wheelchair access methods utilized with children. The clinician
will need to evaluate for the most direct access method possible
through drive trials.

If a child has good head control, we may want to explore a head
array as an option. Access with a head array may take some time for
the child to learn. This can be a more difficult location for access
than the hand. One of the reasons is that there are many additional
commands for the child to remember, such as access to other features
such as power positioning and ECU functions. The child will need to have a
good memory to utilize the head array to access these power wheelchair
functions.

The child will also need to understand that when he or she moves
his or her head, he or she is controlling the power wheelchair. This
can be a foreign concept and may take some time to learn. A long
trial and training period with a power mobility device controlled via
a head array can really make a huge difference in the child's ability to
learn how to operate the chair with the most independence possible.

If upper- and lower-extremity function is absent and head control
is poor, then a good option may be sip and puff. Even a child
who uses a ventilator can utilize a sip and puff system. Contrary
to some people's beliefs, a sip and puff does not require strong
breath support. What it requires to work is good use of oral motor
musculature.

When initiating a puff or a sip, it is performed by changing the
pressure in the user's mouth using the muscles of the mouth to
provide a negative pressure or a positive pressure. As long as the
child can seal his or her lips around the straw and provide a puff
or sip to adequately control the pressures in the system, then he
or she is a potential candidate for power mobility. In addition, if a
child cannot differentiate between a hard and soft sip/puff, then a
two-pressure system could be utilized. This type of system allows
the user to use a double puff and hold for a forward command, a
single puff and hold for a right command, a double sip and hold for a
reverse command and a single sip and hold for a left turn command.
Again, the child must have a good memory in order to remember all
of the commands he or she must use to control the power wheelchair
with this type of driving input system.

Considering Single-Switch Scanning

For children who have a progressive illness and now have limited
consistent movement, or for a child who has significant motor
involvement and only has one consistent movement available, there
is a last resort for independent access: single-switch scanning.

This option has many requirements for independent access. For
success with single-switch scanning to occur, the child must have
good vision, eye scanning, motor planning, and attention span,
which are just the main factors. This is a better option for children
who have never known any other type of mobility, versus adults
and children who may have ambulated or previously used other
access methods for power mobility. Children who have never driven
a power wheelchair before don't know any other type of access to a
power wheelchair, so they typically don't get frustrated with the time
it takes to use single-switch scanning. It is typically individuals who
have used other access methods who find single-switch scanning
frustrating, or even the evaluating team may need to pay attention to
how patient they are during the evaluation period. Provided with the
opportunity, children can be very successful single-switch drivers.

The main thing to remember when performing a pediatric power
mobility evaluation is we need to provide the child with plenty of
time in the wheelchair and a lot of opportunity for success for a
positive outcome to be achieved. This will require significant team
involvement. Therefore, any provider or therapist involved with a
pediatric power mobility evaluation needs to be well vested in that
child becoming a successful driver, because it may take a significant
amount of time before a child is successful. After all, the highest
level of independent mobility is what we all want for any child we
work with.

This article originally appeared in the August 2011 issue of Mobility Management.